Heating dedicated air conditioner

ABSTRACT

A heating dedicated air conditioner includes a compression mechanism, an indoor heat exchanger, an outdoor heat exchanger, an expansion mechanism provided between one end of the indoor heat exchanger and one end of the outdoor heat exchanger, a four-way switching valve switchable between first and second states of connection between the compressor and the heat exchangers, a fan ventilating the indoor heat exchanger, and a control unit controlling at least the compressor, the expansion mechanism, the four-way switching valve, and the fan. The control unit switches the four-way switching valve to the second state in a test operation mode, which includes a drain water inhibited interval during which drain water inhibition control is performed. The control unit operates the compressor and stops the fan when the drain water inhibition control is performed.

TECHNICAL FIELD

The present invention relates to a heating dedicated air conditioner.

BACKGROUND ART

In the conventional art, when an air conditioner is installed, a testoperation is often performed in order to verify whether, for example,the various equipment of the air conditioner operates normally, the airconditioner has been constructed correctly, and the like. For example,in an air conditioner according to Patent Document 1 (i.e., JapaneseUnexamined Patent Application Publication No. 2001-99459), a testoperation is performed in a cooling cycle or a heating cycle;furthermore, in this test operation, a verification is simultaneouslyperformed to determine whether the indoor fan is operating normally.

SUMMARY OF THE INVENTION Technical Problem

Among the air conditioners discussed above, there are heating dedicatedair conditioners that principally perform heating operation. In such aheating dedicated air conditioner, only heating operation is performed,and this principally in the winter season when the temperature is low;therefore, a drainage pipe that serves as drain water processingequipment is often not provided and only a drain pan is provided.Consequently, for example, in the summertime when the temperature andhumidity are high, if a test operation of the heating dedicated airconditioner is performed in a reverse cycle to that of the heating cyclediscussed above, then drain water from the indoor heat exchanger mayoverflow the drain pan and flow into the indoor space, which would be aproblem.

Accordingly, an object of the present invention is to prevent drainwater from an indoor heat exchanger from overflowing a drain pan in acase wherein a test operation of a heating dedicated air conditioner isperformed in a reverse cycle to that of the heating cycle, for example,in summertime when the temperature and humidity are high.

Solution to Problem

A heating dedicated air conditioner according to a first aspect of thepresent invention comprises a compression mechanism, an indoor heatexchanger, an outdoor heat exchanger, an expansion mechanism, a four-wayswitching valve, a fan, and a control unit. The expansion mechanism isprovided between one end of the indoor heat exchanger and one end of theoutdoor heat exchanger. The four-way switching valve switches between afirst state, wherein a discharge side of the compression mechanism andan other end of the indoor heat exchanger are connected and a suctionside of the compression mechanism and an other end of the outdoor heatexchanger are connected, and a second state, wherein the discharge sideof the compression mechanism and the other end of the outdoor heatexchanger are connected and the suction side of the compressionmechanism and the other end of the indoor heat exchanger are connected.The fan ventilates the indoor heat exchanger. The control unit controlsat least the compression mechanism, the expansion mechanism, thefour-way switching valve, and the fan. In addition, the control unit, inthe test operation mode, switches the four-way switching valve to thesecond state. Furthermore, the drain water inhibited interval duringwhich drain water inhibition control is performed, wherein the controlunit operates the compression mechanism and stops the fan, is providedto the test operation mode.

Here, in the heating dedicated air conditioner, if a drain pan isdisposed, for example, below the indoor heat exchanger, then it ispossible to accumulate drain water generated in the indoor heatexchanger. In addition, for example, the expansion mechanism is anexpansion valve whose degree of opening may be fixed.

In the heating dedicated air conditioner according to the first aspectof the invention, the control unit, in the test operation mode, switchesthe four-way switching valve from the first state to the second stateand stops the fan. Thereby, for example, in the heating dedicated airconditioner, it is possible to prevent drain water from overflowing thedrain pan even if the drain pan alone is provided without drainage pipethat externally discharges the drain water accumulated in the drain pan,for example, even if test operation is performed in the summertime in areverse cycle to that of a heating cycle.

A heating dedicated air conditioner according to a second aspect of thepresent invention is the heating dedicated air conditioner according tothe first aspect of the invention, and further comprises a gas sideshutoff valve and a pressure detector. The gas side shutoff valve isprovided between the other end of the indoor heat exchanger and thefour-way switching valve. The pressure detector is mounted to a gasrefrigerant pipe that connects the other end of the indoor heatexchanger and the suction side of the compression mechanism.

In the heating dedicated air conditioner according to the second aspectof the invention, test operation in, for example, the test operationmode is performed in the state wherein the four-way switching valve isin the second state, namely, in the reverse cycle to that of the heatingcycle. This is because, should test operation be performed in theheating cycle, the high pressure between the gas side shutoff valve andthe discharge side of the compression mechanism will tend not to rise,and it might not be possible to promptly detect whether the gas sideshutoff valve is in the open state, which is a problem. Thereby, theopen/close state of the gas side shutoff valve in the test operationmode can be promptly detected by performing, for example, test operationin the test operation mode in the reverse cycle to that of the heatingcycle and providing the pressure detector to the gas refrigerant pipethat connects the other end of the indoor heat exchanger and the suctionside of the compression mechanism.

A heating dedicated air conditioner according to a third aspect of thepresent invention is the heating dedicated air conditioner according tothe second aspect of the invention, and further comprises an indoorcasing and an outdoor casing. The indoor heat exchanger and the fan arehoused in the indoor casing. The compression mechanism, the outdoor heatexchanger, the expansion mechanism, the four-way switching valve, thegas side shutoff valve, and the pressure detector are housed in theoutdoor casing.

In the heating dedicated air conditioner according to the third aspectof the invention, it is possible to prevent the drain water fromoverflowing the drain pan even if test operation is performed in thesummertime.

A heating dedicated air conditioner according to a fourth aspect of thepresent invention is the heating dedicated air conditioner according toany one aspect of the first through third aspects of the invention, andfurther comprises a gas-liquid separator. The gas-liquid separator isprovided between the suction side of the compression mechanism and thefour-way switching valve.

In the heating dedicated air conditioner according to the fourth aspectof the invention, the amount of evaporation of the refrigerant in theindoor heat exchanger decreases because the fan is stopped.Consequently, the amount of the liquid refrigerant increases more thanwhen the fan is operating. Accordingly, providing the gas-liquidseparator makes it possible to prevent the liquid from being sucked intothe compressor.

A heating dedicated air conditioner according to a fifth aspect of thepresent invention is the heating dedicated air conditioner according toany one aspect of the first through fourth aspects of the invention,wherein the drain water inhibited interval occupies 80% or more of theentire interval of the test operation mode.

In the heating dedicated air conditioner according to the fifth aspectof the invention, it is possible to reduce the amount of indoor airdelivered from the fan to the indoor heat exchanger by stopping the fanfor an interval that is 80% or more of the entire interval. Thereby,even if the fan is driven, it is possible to prevent the drain waterfrom overflowing the drain pan.

A heating dedicated air conditioner according to a sixth aspect of thepresent invention is the heating dedicated air conditioner according tothe fifth aspect of the invention, wherein in the test operation mode, afirst interval other than the drain water inhibited interval is abeginning interval of the entire interval of the test operation mode.

In the heating dedicated air conditioner according to the sixth aspectof the invention, the fan is driven during the beginning interval in thetest operation mode when the evaporation temperature does not fall allthat much. Thereby, it is possible to prevent the drain water fromoverflowing the drain pan even if the fan is driven.

Advantageous Effects of Invention

In the heating dedicated air conditioner according to the first aspectof the invention, the control unit, in the test operation mode, switchesthe four-way switching valve from the first state to the second stateand stops the fan. Thereby, for example, in the heating dedicated airconditioner, it is possible to prevent drain water from overflowing thedrain pan even if the drain pan alone is provided without drainage pipethat externally discharges the drain water accumulated in the drain pan,for example, even if test operation is performed in the summertime in areverse cycle to that of a heating cycle.

In the heating dedicated air conditioner according to the second aspectof the invention, the open/close state of the gas side shutoff valve inthe test operation mode can be promptly detected by performing, forexample, test operation in the test operation mode in the reverse cycleto that of the heating cycle and providing the pressure detector to thegas refrigerant pipe that connects the other end of the indoor heatexchanger and the suction side of the compression mechanism.

In the heating dedicated air conditioner according to the third aspectof the invention, it is possible to prevent the drain water fromoverflowing the drain pan even if test operation is performed in thesummertime.

In the heating dedicated air conditioner according to the fourth aspectof the invention, the amount of evaporation of the refrigerant in theindoor heat exchanger decreases because the fan is stopped.Consequently, the amount of the liquid refrigerant increases more thanwhen the fan is operating. Accordingly, providing the gas-liquidseparator makes it possible to prevent the liquid from being sucked intothe compressor.

In the heating dedicated air conditioner according to the fifth andsixth aspects of the invention, even if the fan is driven, it ispossible to prevent the drain water from overflowing the drain pan.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system diagram of a refrigerant circuit of a heatingdedicated air conditioner.

FIG. 2 is a control block diagram of a control unit.

FIG. 3 is a flow chart that illustrates operation during a testoperation of the heating dedicated air conditioner according to a secondembodiment.

DESCRIPTION OF EMBODIMENTS

The embodiments of the present invention will now be explained,referencing the drawings.

First Embodiment <Configuration of Heating Dedicated Air Conditioner 1>

The heating dedicated air conditioner 1 is used to heat an indoor spaceof a building by performing a vapor compression type refrigeration cycleoperation. As shown in FIG. 1, the heating dedicated air conditioner 1comprises a single outdoor unit 2 that serves as a heat source unit, asingle indoor unit 4 that serves as a utilization unit and is connectedto the outdoor unit 2, and a liquid side refrigerant connection pipe 6and a gas side refrigerant connection pipe 7 that serve as refrigerantconnection pipes and connect the outdoor unit 2 and the indoor unit 4.Namely, a refrigerant circuit 10 of the heating dedicated airconditioner 1 is configured by the connection of the outdoor unit 2, theindoor unit 4, the liquid side refrigerant connection pipe 6, and thegas side refrigerant connection pipe 7.

<Configuration of Indoor Unit 4>

First, the configuration of the indoor unit 4 will be explained.

The indoor unit 4 is installed either by embedding it in or suspendingit from the ceiling of the indoor space of a building or by mounting itto a wall surface of the indoor space. The indoor unit 4 is connected tothe outdoor unit 2 via the liquid side refrigerant connection pipe 6 andthe gas side refrigerant connection pipe 7.

The indoor unit 4 principally comprises an indoor side refrigerantcircuit 10 a, which constitutes part of the refrigerant circuit 10. Theindoor side refrigerant circuit 10 a principally comprises an indoorheat exchanger 42.

The indoor heat exchanger 42 is a cross fin type fin and tube heatexchanger, which comprises a heat transfer tube and numerous fins;during heating operation, the indoor heat exchanger 42 functions as acondenser that condenses a refrigerant (e.g., a fluorocarbon basedrefrigerant) and heats indoor air. Furthermore, during defrostingoperation and during test operation, discussed below, (i.e., in thestate wherein the refrigerant circuit 10 is in a reverse cycle to thatof the heating cycle), it functions as an evaporator that evaporates therefrigerant.

In addition, the indoor unit 4 comprises an indoor fan 43 (refer to FIG.2). The indoor fan 43 functions as a ventilation fan, which is forsucking the indoor air into the indoor unit 4, causing heat to beexchanged between that air and the refrigerant in the indoor heatexchanger 42, and then supplying that air to the indoor space as supplyair. In addition, the indoor fan 43 is driven by a fan motor (not shown)and is capable of varying the airflow of the air supplied to the indoorheat exchanger 42. The fan motor is configured such that it is driven byreceiving the supply of electric power via an inverter apparatus (notshown); furthermore, by varying the inverter frequency, which varies thefan rotational speed, the airflow of the indoor fan 43 can be varied.

Furthermore, below the indoor heat exchanger 42, the indoor unit 4 isprovided with a drain pan 45. The drain pan 45 serves to receive anydrain water generated in the indoor heat exchanger 42 in the statewherein the refrigerant circuit 10 is in the reverse cycle to that ofthe heating cycle. Furthermore, a drainage pipe for discharging thedrain water is not provided.

<Configuration of Outdoor Unit 2>

Next, the configuration of the outdoor unit 2 will be explained.

The outdoor unit 2 is installed in the outdoor space outside of abuilding and is connected to the indoor unit 4 via the liquid siderefrigerant connection pipe 6 and the gas side refrigerant connectionpipe 7. Furthermore, the outdoor unit 2 principally comprises an outdoorside refrigerant circuit 10 b, which constitutes part of the refrigerantcircuit 10. The outdoor side refrigerant circuit 10 b principallycomprises: a compressor 21; a four-way switching valve 22; an outdoorheat exchanger 23, which serves as a heat source heat exchanger; anoutdoor expansion valve 24, which serves as an expansion mechanism; anaccumulator 25; a liquid side shutoff valve 26; and a gas side shutoffvalve 27.

The compressor 21 is capable of varying the operating capacity and is adisplacement type compressor that is driven by a compressor motor (notshown).

The four-way switching valve 22 is for the purpose of switching the flowdirection of the refrigerant and can assume a first state (refer to thebroken lines of the four-way switching valve 22 in FIG. 1) and a secondstate (refer to the solid lines of the four-way switching valve 22 inFIG. 1). In the first state, the discharge side of the compressor 21 andthe gas side of the indoor heat exchanger 42 (specifically, the gas siderefrigerant connection pipe 7) are connected, and the suction side ofthe compressor 21 (specifically, the accumulator 25) and the gas side ofthe outdoor heat exchanger 23 are connected. Namely, when the four-wayswitching valve 22 is in the first state, the refrigerant circuit 10 isin the heating cycle. In the second state, the discharge side of thecompressor 21 and the gas side of the outdoor heat exchanger 23 areconnected, and the suction side of the compressor 21 and the gas side ofthe indoor heat exchanger 42 are connected. Namely, when the four-wayswitching valve 22 is in the second state, the refrigerant circuit 10 isin the state wherein it is in the reverse cycle to that of the heatingcycle, that is, in the cooling cycle state.

The outdoor heat exchanger 23 is a cross fin type fin and tube heatexchanger, which comprises heat transfer tubes and numerous fins. Theoutdoor heat exchanger 23 functions as an evaporator that evaporates therefrigerant during the heating operation. The gas side of the outdoorheat exchanger 23 is connected to the four-way switching valve 22, andthe liquid side is connected to the liquid side refrigerant connectionpipe 6. Furthermore, when the four-way switching valve 22 is in thesecond state, the outdoor heat exchanger 23 functions as a condenserthat condenses the refrigerant.

The outdoor expansion valve 24 is a motor operated expansion valve thatis provided between one end of the indoor heat exchanger 42 and one endof the outdoor heat exchanger 23 and is connected to the liquid side ofthe outdoor heat exchanger 23. The outdoor expansion valve 24 regulatesthe pressure, the flow volume, and the like of the refrigerant thatflows through the interior of the outdoor side refrigerant circuit 10 b.

The outdoor unit 2 comprises an outdoor fan 28 (refer to FIG. 2). Theoutdoor fan 28 functions as a ventilation fan, which is for suckingoutdoor air into the outdoor unit 2, causing heat to be exchangedbetween that air and the refrigerant in the outdoor heat exchanger 23,and then discharging that air to the outdoor space. In addition, theoutdoor fan 28 is capable of varying the amount of the outdoor airsupplied to the outdoor heat exchanger 23, and is a propeller fan thatis driven by a fan motor (not shown).

The accumulator 25 is a vessel that is provided between the four-wayswitching valve 22 and the suction side of the compressor 21 and iscapable of accumulating surplus refrigerant generated inside therefrigerant circuit 10 in accordance with fluctuations in the operatingloads of the indoor unit 4.

The liquid side shutoff valve 26 and the gas side shutoff valve 27 areprovided to a connection port that connects to external equipment andpipe (specifically, the liquid side refrigerant connection pipe 6 andthe gas side refrigerant connection pipe 7). The liquid side shutoffvalve 26 is connected to the outdoor heat exchanger 23. The gas sideshutoff valve 27 is connected to the four-way switching valve 22. Theliquid side shutoff valve 26 and the gas side shutoff valve 27 have afunction that seals the refrigerant with which the outdoor unit 2 isinitially filled. Generally, when a builder mounts the heating dedicatedair conditioner 1, he or she completes the refrigerant circuit 10 byconnecting onsite the indoor unit 4 and the outdoor unit 2 using theliquid side refrigerant connection pipe 6 and the gas side refrigerantconnection pipe 7 and, afterward, manually sets the liquid side shutoffvalve 26 and the gas side shutoff valve 27 to an open state. Thereby,the refrigerant that is sealed inside the outdoor unit 2 (specifically,the outdoor heat exchanger 23) is made to spread to the refrigerantcircuit 10.

In addition, the outdoor unit 2 is provided with a refrigerant pressuresensor 33, which detects the pressure of the refrigerant between thefour-way switching valve 22 and the gas side shutoff valve 27.

<Configuration of Liquid Side Refrigerant Connection Pipe 6 and Gas SideRefrigerant Connection Pipe 7>

The liquid side refrigerant connection pipe 6 and the gas siderefrigerant connection pipe 7 are refrigerant pipes that are laid onsitewhen the heating dedicated air conditioner 1 is installed at aninstallation location inside a building; refrigerant pipes of variouslengths and diameters are used for the pipes 6, 7 in accordance with theinstallation conditions such as the installation location and theparticular combination of the outdoor unit 2 and indoor unit 4 to beconfigured.

<Configuration of Control Unit 9>

A control unit 9 comprises a microcomputer, memory, and the like and, asshown in FIG. 2, comprises an indoor control unit 9 a and an outdoorcontrol unit 9 b. The indoor control unit 9 a controls the operation ofthe various equipment (specifically, the indoor fan 43 and the like)that constitutes the indoor unit 4. The outdoor control unit 9 bcontrols the operation of the various equipment (specifically, thecompressor 21, the outdoor fan 28, and the like) that constitutes theoutdoor unit 2.

The indoor control unit 9 a is capable of transmitting control signalsto and receiving control signals from a remote controller (not shown),which is for separately operating the indoor unit 4. In addition, theindoor control unit 9 a and the outdoor control unit 9 b are configuredsuch that they can transmit control signals between and receive controlsignals from one another via a transmission line. Furthermore, thecontrol unit 9, which comprises the indoor control unit 9 a and theoutdoor control unit 9 b, is connected to the refrigerant pressuresensor 33 such that the control unit 9 can receive a detection signaltherefrom and is configured such that it can control the rotationalspeed of the indoor fan 43 and the outdoor fan 28, the rotational speedof the compressor 21, and the like based on the detection signal, acontrol signal from the remote controller, and the like.

Furthermore, prescribed threshold values are set in the control unit 9for the low pressure side pressure and the high pressure side pressuredetected by the refrigerant pressure sensor 33, and fluctuations, eitherupward or downward, in the low pressure side pressure and the highpressure side pressure are detected on the basis of these thresholdvalues. Furthermore, this detection makes it possible to know whetherthere is an abnormal condition in any of the various equipment of theheating dedicated air conditioner 1. For example, during a testoperation in a test operation mode, discussed below, when the gas sideshutoff valve 27 is in not the open but the closed state, the pressuredetected by the refrigerant pressure sensor 33 falls below the thresholdvalue of the low pressure side pressure.

<Operation of Heating Dedicated Air Conditioner 1>

The principal operation Modes of the heating dedicated air conditioner 1are a normal operation mode, wherein the various equipment of theoutdoor unit 2 and the indoor unit 4 is controlled in accordance withthe operating load of the indoor unit 4, and the test operation mode,which is for verifying, for example, whether the various equipment ofthe outdoor unit 2 and the indoor unit 4 is operating normally, andwhether the construction is correct (e.g., whether the liquid sideshutoff valve 26 and the gas side shutoff valve 27 are in the openstate). In the normal operation mode, heating operation is principallyperformed. In the test operation mode, test operation is performed.Furthermore, test operation is performed after the installation of thevarious equipment of the heating dedicated air conditioner 1(specifically, test operation is not limited to being performed afterthe initial installation of the equipment, and may be performed, forexample, after making modifications such as adding or removing variousequipment of the outdoor unit 2 and the indoor unit 4, after repairingan equipment failure, and the like).

The following text explains the operation of the heating dedicated airconditioner 1 in each of the operation modes, referencing FIG. 1.Furthermore, the operation of the heating dedicated air conditioner 1 isperformed by the control unit 9.

(1) Normal Operation Mode (a) Heating Operation

First, heating operation in the normal operation mode will be explained.

During heating operation, control is performed such that the four-wayswitching valve 22 is in the first state. Namely, the four-way switchingvalve 22 is controlled such that the state obtains wherein the dischargeside of the compressor 21 is connected to the gas side of the indoorheat exchanger 42 via the gas side shutoff valve 27 and the gas siderefrigerant connection pipe 7, and the suction side of the compressor 21is connected to the gas side of the outdoor heat exchanger 23.

Furthermore, in this state, if the compressor 21, the outdoor fan 28,and the indoor fan 43 are driven, then the low pressure gas refrigerantis suctioned into the compressor 21 and therefore is compressed andtransitions to high pressure gas refrigerant. This high pressure gasrefrigerant is delivered to the indoor unit 4 via the four-way switchingvalve 22, the gas side shutoff valve 27, and the gas side refrigerantconnection pipe 7. In the indoor heat exchanger 42, the heat of the highpressure gas refrigerant delivered to the indoor unit 4 is exchangedwith the indoor air supplied by the indoor fan 43, and thereby thatrefrigerant is condensed and transitions to high pressure liquidrefrigerant. The high pressure liquid refrigerant is delivered to theoutdoor unit 2 via the liquid side refrigerant connection pipe 6 and theliquid side shutoff valve 26. Furthermore, the pressure of the highpressure liquid refrigerant delivered to the outdoor unit 2 is reducedby the outdoor expansion valve 24, and that refrigerant transitions torefrigerant in a low pressure gas-liquid two-phase state and isdelivered to the outdoor heat exchanger 23. In the outdoor heatexchanger 23, the heat of the liquid refrigerant in the low pressuregas-liquid two-phase state is exchanged with the outdoor air supplied bythe outdoor fan 28, and thereby that refrigerant evaporates andtransitions to low pressure gas refrigerant. This low pressure gasrefrigerant flows into the accumulator 25 via the four-way switchingvalve 22 and then once again is suctioned into the compressor 21.

Accordingly, the outdoor heat exchanger 23 functions as an evaporatorthat evaporates the refrigerant. However, if the heating operation ofthe heating dedicated air conditioner 1 is performed under the conditionwherein the temperature of the outdoor air, which is the heat source ofthe outdoor heat exchanger 23, is low, then one can assume that frostwill adhere to the surface of the outdoor heat exchanger. Furthermore,if frost does adhere to the surface of the outdoor heat exchanger, thenthere is a risk that the heat exchange performance of the outdoor heatexchanger will decrease. Accordingly, in the heating dedicated airconditioner 1, when frost adheres to the outdoor heat exchanger 23during heating operation, the four-way switching valve 22 is temporarilyswitched from the first state to the second state and defrostingoperation is performed as below.

(b) Defrosting Operation

During defrosting operation, control is performed such that the four-wayswitching valve 22 is in the second state. Namely, the four-wayswitching valve 22 is controlled such that a state obtains wherein thedischarge side of the compressor 21 is connected to the gas side of theoutdoor heat exchanger 23, and the suction side of the compressor 21 isconnected to the gas side of the indoor heat exchanger 42 via the gasside shutoff valve 27 and the gas side refrigerant connection pipe 7.

In this state, if the compressor 21 is driven, first, the low pressuregas refrigerant is suctioned into the compressor 21 where it iscompressed and transitions to high pressure gas refrigerant.Furthermore, the high pressure gas refrigerant is delivered to theoutdoor heat exchanger 23 via the four-way switching valve 22, its heatis exchanged with the outdoor air in the outdoor heat exchanger 23, andthereby condenses and transitions to high pressure liquid refrigerant.At this time, the frost or the ice that adheres to the surface of theoutdoor heat exchanger 23 melts owing to the heat emitted from the highpressure gas refrigerant, which is undergoing the heat exchange process.Furthermore, during defrosting operation, control is performed such thatthe outdoor fan 28 is in the stopped state.

Furthermore, the outdoor expansion valve 24 reduces the pressure of thehigh pressure liquid refrigerant, which transitions to refrigerant inthe low pressure gas-liquid two-phase state and is delivered to theindoor unit 4 via the liquid side shutoff valve 26 and the liquid siderefrigerant connection pipe 6. The refrigerant in the low pressuregas-liquid two-phase state delivered to the indoor unit 4 is thendelivered to the indoor heat exchanger 42; the heat of that refrigerantis exchanged with the indoor air at the indoor heat exchanger 42, andthereby that refrigerant evaporates and transitions to low pressure gasrefrigerant. At this time, the indoor fan 43 is controlled such that itis in the stopped state. This is done in order to prevent cold air frompotentially being blown out into the indoor space when the indoor fan 43is operating, thereby reducing the comfort of users of the indoor space.

Furthermore, the low pressure gas refrigerant is delivered to theoutdoor unit 2 via the gas side refrigerant connection pipe 7 and thegas side shutoff valve 27, and then flows into the accumulator 25 viathe four-way switching valve 22. Furthermore, the low pressure liquidrefrigerant that does not evaporate at the indoor heat exchanger 42because the indoor fan 43 is stopped accumulates in the accumulator 25.

Furthermore, the low pressure gas refrigerant that flows into theaccumulator 25 is once again sucked into the compressor 21.

(2) Test Operation Mode

Test operation in the test operation mode will be explained next. Notethat test operation is performed by a worker operating an operationbutton, which is provided to a remote controller (not shown) and is forsetting the operation mode to the test operation mode. In addition, thetest operation interval, which is the entire interval during which testoperation is performed in the test operation mode, is set in advance(e.g., to three minutes);

furthermore, when the set test operation interval ends, the modeswitches to the operation mode set by the user via the remote controller(i.e., to heating operation in the normal operation mode).

Here, ordinarily, test operation is often performed in the state whereinthe four-way switching valve 22 is controlled such that it is in thesecond state (i.e., when the refrigerant circuit is in the so-calledcooling cycle state). This is because if test operation is performedduring the heating cycle, then the pressure detected by the refrigerantpressure sensor 33 will tend not to rise, and consequently it couldbecome difficult to promptly detect whether the shutoff valve (e.g., thegas side shutoff valve 27) is in the open state.

However, in a heating dedicated air conditioner, drainage work, such asfor discharging drain water accumulated in a drain pan to the outdoorspace, is often not undertaken. Consequently, if the heating dedicatedair conditioner is used and test operation is performed during thecooling cycle in, for example, a high temperature and high humiditylocation or during a high temperature and high humidity season (e.g.,summertime), then the refrigerant that flows through the interior of anindoor heat exchanger will take the heat of the indoor air delivered tothe indoor heat exchanger by an indoor fan, and thereby a large amountof drain water is assumed to be generated in the indoor heat exchanger.Therefore, even if the drain water generated in the indoor heatexchanger could be accumulated in the drain pan, if the amount of thedrain water exceeds the capacity of the drain pan to store water, thenit is conceivable that the drain water will overflow the drain pan andflow into the indoor space.

Accordingly, during test operation of the heating dedicated airconditioner 1, drain water inhibition control, which operates thecompressor 21 and stops the indoor fan 43, is performed. A drain waterinhibited interval, during which drain water inhibition control isperformed, is the same as the test operation interval. Namely, in theheating dedicated air conditioner 1, the indoor fan 43 is always stoppedduring test operation in the test operation mode.

Thereby, the generation of drain water is inhibited because the heatexchange efficiency between the refrigerant and the indoor air in theindoor heat exchanger 42 is lower than when the indoor fan 43 is beingoperated. Thereby, it is possible to prevent the drain water fromoverflowing the drain pan 45.

Furthermore, the operation of the heating dedicated air conditioner 1during test operation is substantially the same as the operation of theheating dedicated air conditioner 1 during defrosting operation.However, during defrosting operation, the outdoor fan 28 is stopped,whereas, during test operation, the outdoor fan 28 is operated and thedegree of opening of the outdoor expansion valve 24 is fixed.

<Characteristics of Heating Dedicated Air Conditioner 1 According to theFirst Embodiment>

(1)

In the first embodiment, test operation is performed in the statewherein the four-way switching valve 22 is in the second state.Furthermore, during test operation, the indoor fan 43 is stopped.

Thereby, the indoor fan 43 no longer delivers the indoor air to theindoor heat exchanger 42, and therefore the amount of the indoor airwhose heat is exchanged with the refrigerant in the indoor heatexchanger 42 decreases. Accordingly, because the drain water generatedin the indoor heat exchanger 42 also decreases, it becomes possible toprevent the drain water from overflowing the drain pan 45, even duringthe summer. In addition, because the drain water does not overflow thedrain pan 45, it is possible to also prevent the drain water fromflowing into the indoor space. In addition, drain work also therebybecomes unnecessary.

(2)

In the first embodiment, the indoor fan 43 is stopped during testoperation and during defrosting operation. Consequently, the amount ofevaporation of the refrigerant flowing through the indoor heat exchanger42 is assumed to be less than when the indoor fan 43 is being operated.Furthermore, it is conceivable that the reduced amount of evaporation ofthe refrigerant flowing through the indoor heat exchanger 42 causes notonly the gas refrigerant but also the refrigerant in the gas-liquidtwo-phase state to flow out of the indoor heat exchanger 42 and to theoutdoor unit 2 side.

Accordingly, because the provision of the accumulator 25 between thesuction side of the compressor 21 and the four-way switching valve 22makes it possible to accumulate the liquid refrigerant in theaccumulator 25 even if the refrigerant in the gas-liquid two-phase stateflows to the outdoor unit 2 side, it is possible to cause the gasrefrigerant alone to be suctioned to the compressor 21. Thereby, it ispossible to prevent damage to the compressor 21.

<Modified Example of Heating Dedicated Air Conditioner 1 According tothe First Embodiment>

The above text explained an embodiment of the present invention based onthe drawings, but the specific constitution is not limited to thatembodiment, and it is understood that variations and modifications maybe effected without departing from the spirit and scope of theinvention.

(A)

The abovementioned embodiment explained a case that is limited to aseparate type heating dedicated air conditioner 1, wherein one indoorunit 4 is connected to one outdoor unit 2, but the present invention isnot limited thereto; for example, the present invention may be adaptedto an integrated type heating dedicated air conditioner, wherein theoutdoor unit 2 and the indoor unit 4 are integrated.

In addition, the abovementioned embodiment explained a case limited to aso-called paired heating dedicated air conditioner 1, wherein one indoorunit 4 is connected to one outdoor unit 2, but the present invention isnot limited thereto. For example, the present invention may be adaptedto a so-called multi type heating dedicated air conditioner, wherein aplurality of the indoor units is connected to one outdoor unit 2.

(B)

In the abovementioned embodiment, the refrigerant is not limited tofluorocarbon based refrigerant, and may be a natural refrigerant such asCO₂ refrigerant.

Second Embodiment

Continuing, a second embodiment of the heating dedicated air conditioner1 will now be explained. Note that components and the like identical tothose in the first embodiment are assigned the same symbols, andexplanations thereof are therefore omitted.

The second embodiment differs from the first embodiment as follows: inthe first embodiment, the indoor fan 43 is always stopped during testoperation in the test operation mode; however, in the second embodiment,there is a case wherein the indoor fan 43 is operated, and is not alwaysstopped, during test operation.

The text below explains the operation during test operation of theheating dedicated air conditioner 1 in the second embodiment,referencing FIG. 3.

FIG. 3 is a flow chart that illustrates operation during test operationof the heating dedicated air conditioner 1 according to the secondembodiment.

First, in a step S101, the four-way switching valve 22 is controlledsuch that it is in the second state, as in the first embodiment.Furthermore, in a step S102, the compressor 21 and the outdoor fan 28are driven, as in the first embodiment. At this time, in the firstembodiment, the indoor fan 43 is always stopped during test operation inthe test operation mode, and consequently the indoor fan 43 is notdriven; however, in the second embodiment, the indoor fan 43 is drivenin addition to the compressor 21 and the outdoor fan 28.

Next, in a step S103, it is determined whether the indoor fan 43 isoperating normally. If it is determined that it is operating normally,then the process transitions to a step S104; if, however, it isdetermined that it is not operating normally, then the processtransitions to a step S105.

In the step S104, drain water inhibition control is performed, as in thefirst embodiment. Namely, the compressor 21 maintains its operationstate as is, and the indoor fan 43 stops.

In the step S105, it has been determined that the indoor fan 43 is notoperating normally, and therefore a warning is displayed via a reportingunit (not shown; e.g., an LED or a character display).

Accordingly, in the heating dedicated air conditioner 1 according to thesecond embodiment, the interval during which the indoor fan 43 is driven(corresponding to a first interval) is approximately 5-10 s. Thereby,the drain water inhibited interval, which is the interval during whichthe drain water inhibition control is performed, occupies 80% or more(specifically, approximately 94%-97%) of the test operation interval(e.g., 3 minutes).

In addition, as discussed above, the interval during which the indoorfan 43 is driven is the beginning interval in the test operationinterval. This is because drain water tends to be generated if theindoor fan 43 is driven when the evaporation temperature has fallen.

Furthermore, as in the indoor fan 43, a warning is displayed even if thecompressor 21, the outdoor fan 28, or the like is not being drivennormally.

<Characteristics of Heating Dedicated Air Conditioner 1 According to theSecond Embodiment>

In the heating dedicated air conditioner 1 according to the secondembodiment, the indoor fan 43 can be driven during test operation in thetest operation mode, which is effective if, for example, one wishes toverify whether the indoor fan 43 is operating normally.

In addition, in the heating dedicated air conditioner 1 according to thesecond embodiment, the drain water inhibited interval, which is theinterval during which drain water inhibition control is performed,occupies 80% or more of the test operation interval.

During test operation in the test operation mode, it is possible toreduce the amount of the indoor air delivered from the indoor fan 43 tothe indoor heat exchanger 42 by stopping the indoor fan 43 for aninterval that is 80% or more of the entire interval. Thereby, the amountof drain water generated in the indoor heat exchanger 42 decreases.Accordingly, even if the indoor fan 43 is driven in order to verifywhether the indoor fan 43 is operating normally, it is still possible toprevent the drain water from overflowing the drain pan 45.

In addition, in the heating dedicated air conditioner 1 according to thesecond embodiment, the interval during which the indoor fan 43 is drivenis the beginning interval in the test operation interval. Namely, theindoor fan 43 is driven in the beginning interval during test operationwhen the evaporation temperature does not drop all that much. Thereby,it is possible to prevent the drain water from overflowing the drain pan45 even if the indoor fan 43 is driven in order to verify whether theindoor fan 43 is operating normally. In addition, drain work alsothereby becomes unnecessary.

<Modified Example of the Heating Dedicated Air Conditioner 1 Accordingto the Second Embodiment>

In the abovementioned embodiments, the indoor fan 43 is driven in orderto verify whether it is operating normally, but the present invention isnot limited thereto; the indoor fan 43 may be driven as discussed abovefor some other purpose. Even so, the same effects as those discussedabove are obtained.

INDUSTRIAL APPLICABILITY

In the present invention, if test operation of the heating dedicated airconditioner is performed in the reverse cycle to that of the heatingcycle in, for example, summertime when the temperature and humidity arehigh, then it is possible to prevent drain water generated in the indoorheat exchanger from overflowing the drain pan, thereby making drain workunnecessary, which is useful.

REFERENCE SIGNS LIST

-   1 Heating dedicated air conditioner-   2 Outdoor casing (outdoor unit)-   4 Indoor casing (indoor unit)-   7 Gas side refrigerant connection pipe (gas refrigerant pipe)-   9 Control unit-   21 Compressor (compression mechanism)-   22 Four-way switching valve-   23 Outdoor heat exchanger-   24 Outdoor expansion valve (expansion mechanism)-   25 Accumulator (gas-liquid separator)-   27 Gas side shutoff valve-   33 Refrigerant pressure sensor (pressure detector)-   42 Indoor heat exchanger-   43 Indoor fan (fan)

CITATION LIST Patent Literature Patent Document 1

Japanese Unexamined Patent Application Publication No. 2001-99459

1. A heating dedicated air conditioner, comprising: a compressionmechanism; an indoor heat exchanger; an outdoor heat exchanger; anexpansion mechanism disposed between one end of the indoor heatexchanger and one end of the outdoor heat exchanger; a four-wayswitching valve switchable between a first state in which a dischargeside of the compression mechanism and an other end of the indoor heatexchanger are connected and a suction side of the compression mechanismand an other end of the outdoor heat exchanger are connected, and asecond state in which the discharge side of the compression mechanismand the other end of the outdoor heat exchanger are connected and thesuction side of the compression mechanism and the other end of theindoor heat exchanger are connected; a fan arranged to ventilate theindoor heat exchanger; and a control unit configured to control at leastthe compression mechanism, the expansion mechanism, the four-wayswitching valve, and the fan, the control unit being configured toswitch the four-way switching valve to the second state in a testoperation mode, the test operation mode including a drain waterinhibited interval during which drain water inhibition control isperformed, the control unit being configured to operate the compressionmechanism and stop the fan when the drain water inhibition control isperformed.
 2. The heating dedicated air conditioner according to claim1, further comprising: a gas side shutoff valve disposed between theother end of the indoor heat exchanger and the four-way switching valve;and a pressure detector mounted to a gas refrigerant pipe, the gasrefrigerant pipe connecting the other end of the indoor heat exchangerand the suction side of the compression mechanism.
 3. The heatingdedicated air conditioner according to claim 2, further comprising: anindoor casing; and an outdoor casing; wherein, the indoor heat exchangerand the fan being housed in the indoor casing, and the compressionmechanism, the outdoor heat exchanger, the expansion mechanism, thefour-way switching valve, the gas side shutoff valve, and the pressuredetector being housed in the outdoor casing.
 4. The heating dedicatedair conditioner according to claim 1, further comprising: a gas-liquidseparator disposed between the suction side of the compression mechanismand the four-way switching valve.
 5. The heating dedicated airconditioner according to claim 1 wherein the drain water inhibitedinterval occupies 80% or more of the entire interval of the testoperation mode.
 6. The heating dedicated air conditioner according toclaim 5, wherein a first interval other than the drain water inhibitedinterval is a beginning interval of the entire interval of the testoperation mode.
 7. The heating dedicated air conditioner according toclaim 4, wherein the drain water inhibited interval occupies 80% or moreof the entire interval of the test operation mode.
 8. The heatingdedicated air conditioner according to claim 7, wherein a first intervalother than the drain water inhibited interval is a beginning interval ofthe entire interval of the test operation mode.
 9. The heating dedicatedair conditioner according to claim 2, further comprising: a gas-liquidseparator disposed between the suction side of the compression mechanismand the four-way switching valve.
 10. The heating dedicated airconditioner according to claim 2, wherein the drain water inhibitedinterval occupies 80% or more of the entire interval of the testoperation mode.
 11. The heating dedicated air conditioner according toclaim 10, wherein a first interval other than the drain water inhibitedinterval is a beginning interval of the entire interval of the testoperation mode.
 12. The heating dedicated air conditioner according toclaim 3, further comprising: a gas-liquid separator disposed between thesuction side of the compression mechanism and the four-way switchingvalve.
 13. The heating dedicated air conditioner according to claim 3,wherein the drain water inhibited interval occupies 80% or more of theentire interval of the test operation mode.
 14. The heating dedicatedair conditioner according to claim 13, wherein a first interval otherthan the drain water inhibited interval is a beginning interval of theentire interval of the test operation mode.